Vehicles equipped with automated transmissions and automated clutches have been on the market for a long time. Preferred fields of use here are commercially used vehicles such as passenger cars, vans or trucks. In the recent past, passenger cars used in sports or light cars have been increasingly equipped with such transmissions or clutches. The aim is to relieve the driver from gear changes and altogether make a more comfortable and reliable operation possible. Vehicles with those transmissions usually have two pedals; an accelerator pedal and a brake pedal. The clutch pedal can be eliminated. In the vehicle, a selector switch is available for choosing the mode of operation. It is possible to select among an automatic mode, a manual selector mode and reverse gear. If the automatic mode is chosen, the ratio is automatically adapted. Different solutions exist for the automation of transmissions and clutches, especially in the field of commercial vehicles. There are different alternatives such as pneumatic, hydraulic or purely electric systems. Which alternative to select essentially depends on the kind of vehicle and on the types of energy available in said vehicle. The power requirement of the actuators used is another important parameter. Depending on the system, there are used as actuators pneumatic or hydraulic cylinders or electric motor which, via transmissions, drive the selector and shift devices and the actuating devices for the clutch. Actuators which are driven by electric motors constitute constructions which are especially favorable because of their cost.
Accumulators needed in the clutch operation for power assistance combined with the use of a recirculating ball spindle as driving element are usually situated close to the recirculating ball spindle or surrounding the recirculating ball spindle. If the accumulator is placed next to the recirculating ball spindle, the power has to be reversed by means of levers. But if the accumulator surrounds the recirculating ball spindle, then the diameter of the recirculating ball spindle takes a predominant part in the dimensional layout of the accumulator given by the spring internal diameter. The former solutions where displacement sensors are combined with recirculating ball spindles give the impression that the displacement sensor must be disposed parallel with the recirculating ball spindle or in a parallel position relative to another part. If the displacement sensor is disposed parallel with the recirculating ball spindle, additional space is needed and the mounting of the transmission means such as the magnet is difficult. If the displacement sensor is disposed parallel with another part, the part has to be in the same operational axis as the recirculating ball spindle. Thereby the installation space needed for the construction is lengthened.
DE 44 33 824 C2 has disclosed, by way of example, one actuating device for a friction clutch of a motor vehicle which has one drive mechanism and one crankshaft gear that converts the movement of the drive shaft thereof to an essentially translatory movement of an output element. The crankshaft gear is designed as a worm gear with one worm sitting upon the drive shaft and meshing with one tooth segment of one segment gear wheel rotatably supported in one housing. On the segment worm gear wheel laterally engages one preload element with one spring device. The spring device springs back under expansion out of a predeterminable dead center position, whereby the releasing direction is in such a manner being selected so that the tension has at least one essential component in deflection direction of the contact spring of the friction clutch which can be deflected from its operative position by the output element, designed as a hydraulic master cylinder, via a slave cylinder (not shown). Thereby the spring device of the preload element assists, as accumulator, the drive mechanism during the movement thereof so that the drive mechanism can be designed as relatively low-powered.
The problem on which the invention is based is to arrange the accumulator in a space-saving manner in an actuating device.